This invention relates to a magnetic recording system for recording and reproducing data with respect to a specified track section among a plurality of recording tracks formed on a magnetic recording medium in a predetermined direction thereof.
The magnetic recording system is presently one of the most effective systems for recording such data as image data, voice data or digital data which is provided from a computer. Video tape recorders (VTR) for recording and reproducing image signals, for instance, usually adopt a rotary head system. In the rotary head type VTR, however, the mechanism for accurately driving a head section for rotation is complicated and involves a large number of component parts, so that its manufacturing cost is high.
In order to solve this problem, a magnetic recording system based on a so-called stationary head system has been proposed. With the stationary head system, a plurality of parallel recording tracks are formed on a magnetic recording medium, for instance a magnetic tape of an endless tape unit, in a predetermined direction of running of the tape. In the recording/reproducing mode, various heads of the head section are moved in a direction substantially perpendicular to the direction of the recording tracks, i.e., in the direction of the tape width, and brought to a position corresponding to a desired track for recording, reproduction or erasing of data. In the stationary head type magnetic recording system mentioned above, two heads, i.e., a recording/reproducing head and an erasing head, for instance, are provided.
In the prior art, the recording/reproducing head and erasing head have their respective recording/reproducing width (which corresponds to the core width and referred to in the specification as operating width) and erasing width set to correspond to the width of one recording track. When performing the so-called rerecording (i.e. erasing old data and recording new data), the data that has already been recorded on a magnetic tape is erased and, in place of the erased data, new data is recorded over a specified track section from a given track position. The aforementioned heads are moved to a position which does not precisely correspond to but is more or less deviated from the specified start track. This results from the fluctuations in the precision of the component parts, the precision of assembly of individual units and also errors produced due to vibrations occurring in the direction of the tape width when the tape is run. Therefore, when the recording is made under the aforementioned circumstances, excessive erasure or insufficient erasure of data results. Thus, with the aforementioned deviation from the track, the erasure of one track has adverse effects upon an adjacent track in addition to the possibility of the excessive erasure or insufficient erasure as mentioned above.